Unit C: Treasures From Earth
1. Get Set to Explore
- liquid: State of matter in which the material has a set size but no set shape; liquids flow and can be poured.
- mineral: A nonliving solid found in nature.
- rock: A solid made of one or more minerals.
- Bring in rocks and minerals for children to examine. Tell children which samples are rocks and which are minerals. Then have children try to figure out what the difference is between rocks and minerals. Write their ideas on the board. After students have compared the rocks and minerals, define or review the definitions of these terms. Let students correct the ideas they had after they examined the rock and mineral samples.
- Point out that the minerals in rocks are used to make many different things. The minerals are often changed by heating and melting. Explain that heating some minerals to very high temperatures causes them to melt, becoming a liquid.
- Present the Discover! question and ask children what they think the answer might be. If they have difficulty coming up with answers, remind them of the idea of changing minerals by heating them. Write children's ideas on the board.
2. Guide the Exploration
- Have children launch the Discover! Simulation and listen closely to the directions. If necessary, they can play the beginning over again by clicking the Listen button
- Give children the Word Web graphic organizer. In the large circle, have them write the word glass. Then prompt them to list the different ingredients needed to make glass. For each ingredient, they should give its function. They can add a fourth circle to tell what they added to color the glass. You may wish to point out that the substances used to color glass are different metals or minerals.
- After children have selected all the necessary ingredients, ask them why the materials need to be crushed and mixed before glass-making can proceed. Guide them to understand that glass ingredients need to be well-mixed for the same reason that ingredients in a cake need to be well-mixed: so that the final product is of good quality and is the same (uniform) throughout.
- Direct children to note the furnace's rising temperature. Ask volunteers to predict how the materials will change. Have children finish watching the simulation.
- Review Step 3's Wrap-Up text with the class. Ask children to share any observations or questions that they have.
- Have a volunteer tell what is added to glass to cause it to become colored. Guide children to recognize that the different colors result from different minerals or different metals being added to the glass while it is being made.
- Present the Extension question to the class. Ask children: How would you make clear glass like the kind you find in windows?
- Encourage children to relate the color of the glass to extra ingredients (minerals or metals) that are added to the glass. Based on this information, they should infer that clear glass is made of only three ingredients—sand, soda ash, and limestone–and has no extra ingredients added.
If time permits, present children with the following questions and activities:
- Critical Thinking Apply One kind of glass, called obsidian, can form naturally. Where do you think obsidian forms? Answer: Obsidian forms during or right after a volcanic eruption. The main ingredient in glass—sand (silica)—is common in and near mountains; volcanoes can be hot enough to melt the sand, causing the formation of glass.
- Inquiry Skill Observe Look at home or at school for different items made of glass. For each item, write the color of the glass. Share what you observed, and make a class list of all the different types of glass items.
4. Reaching All Learners
On Level: Linguistic Learners
Print a copy of the simulation screen that shows the ingredients, the crusher, the furnace, and the final product. Encourage linguistic learners to use the printed page while they listen and watch the simulation to take notes on the different steps of the process. If you have time, go over and help linguistic learners correct their annotated diagrams. Then these children can share their diagrams, one on one, with other children who might benefit from reviewing the glass-making process step by step, without any distractions from screen movement or sounds.